我在 Android 上的第一个应用程序有点问题。我一直在搜索有关如何使用传感器事件的所有信息，但是每次打开我的应用程序时我都会遇到 FC。
logcat 说：
02-26 05:45:55.291 I/ActivityManager(4935): Displayed me.das4ilor.fortunetellerfull/.MainActivity: +1s311ms
02-26 05:45:55.385 W/NetworkManagementSocketTagger(4935): setKernelCountSet(10056, 0) failed with errno -2
02-26 05:45:55.494 D/AndroidRuntime(19501): Shutting down VM
02-26 05:45:55.494 W/dalvikvm(19501): threadid=1: thread exiting with uncaught exception (group=0x40a031f8)
02-26 05:45:55.533 E/AndroidRuntime(19501): FATAL EXCEPTION: main
02-26 05:45:55.533 E/AndroidRuntime(19501): java.lang.NullPointerException
02-26 05:45:55.533 E/AndroidRuntime(19501): at me.das4ilor.fortunetellerfull.MainActivity$1.onAccuracyChanged(MainActivity.java:58)
02-26 05:45:55.533 E/AndroidRuntime(19501): at android.hardware.SensorManager$ListenerDelegate$1.handleMessage(SensorManager.java:574)
02-26 05:45:55.533 E/AndroidRuntime(19501): at android.os.Handler.dispatchMessage(Handler.java:99)
02-26 05:45:55.533 E/AndroidRuntime(19501): at android.os.Looper.loop(Looper.java:137)
02-26 05:45:55.533 E/AndroidRuntime(19501): at android.app.ActivityThread.main(ActivityThread.java:4575)
02-26 05:45:55.533 E/AndroidRuntime(19501): at java.lang.reflect.Method.invokeNative(Native Method)
02-26 05:45:55.533 E/AndroidRuntime(19501): at java.lang.reflect.Method.invoke(Method.java:511)
02-26 05:45:55.533 E/AndroidRuntime(19501): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:789)
02-26 05:45:55.533 E/AndroidRuntime(19501): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:556)
02-26 05:45:55.533 E/AndroidRuntime(19501): at dalvik.system.NativeStart.main(Native Method)
02-26 05:45:55.533 W/ActivityManager(4935): Force finishing activity me.das4ilor.fortunetellerfull/.MainActivity
这是 .java ：
package me.das4ilor.fortunetellerfull;
import me.das4ilor.fortunetellerfull.R;
import android.hardware.Sensor;
import android.hardware.SensorEvent;
import android.hardware.SensorEventListener;
import android.hardware.SensorManager;
import android.os.Bundle;
import android.app.Activity;
import android.content.Context;
import android.widget.TextView;
import android.widget.Toast;
import java.util.Random;
public class MainActivity extends Activity {
public static final Random rgenerator = new Random();
private SensorManager mSensorManager;
private float mAccel;
private float mAccelCurrent;
private float mAccelLast;
private TextView textView2;
private String[] myString;
Context context = this;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
Toast.makeText(context, "Thank you for buying full version!", Toast.LENGTH_SHORT).show();
mSensorManager = (SensorManager) getSystemService(Context.SENSOR_SERVICE);
mSensorManager.registerListener(mSensorListener, mSensorManager.getDefaultSensor(Sensor.TYPE_ACCELEROMETER), SensorManager.SENSOR_DELAY_NORMAL);
mAccel = 0.00f;
mAccelCurrent = SensorManager.GRAVITY_EARTH;
mAccelLast = SensorManager.GRAVITY_EARTH;
}
private final SensorEventListener mSensorListener = new SensorEventListener() {
public void onSensorChanged(SensorEvent se) {
float x = se.values[0];
float y = se.values[1];
float z = se.values[2];
mAccelLast = mAccelCurrent;
mAccelCurrent = (float) Math.sqrt((double) (x*x + y*y + z*z));
float delta = mAccelCurrent - mAccelLast;
mAccel = mAccel * 0.9f + delta;
}
public void onAccuracyChanged(Sensor sensor, int accuracy) {
myString = getResources().getStringArray(R.array.String);
String q = myString[rgenerator.nextInt(myString.length)];
textView2.setText(q);
}
};
@Override
protected void onResume() {
super.onResume();
mSensorManager.registerListener(mSensorListener, mSensorManager.getDefaultSensor(Sensor.TYPE_ACCELEROMETER), SensorManager.SENSOR_DELAY_NORMAL);
}
@Override
protected void onPause() {
mSensorManager.unregisterListener(mSensorListener);
super.onPause();
}
}